Nuts
heavy hex
Dimensional Information
F
H
G
Heavy Hex Nuts
Nominal Size or Basic
Major Diameter of Thread
160
ASME
B18.2.2
F
G
H
Width Across Flats
Width Across Corners
Thickness
Basic
Max
Min
Max
Min
Basic
Max
Min
1/4
0.2500
1/2
0.500
0.488
0.577
0.556
15/64
0.250
0.218
5/16
0.3125
9/16
0.562
0.546
0.650
0.622
19/64
0.314
0.280
3/8
0.3750
11/16
0.688
0.669
0.794
0.763
23/64
0.377
0.341
7/16
0.4375
3/4
0.750
0.728
0.866
0.830
27/64
0.441
0.403
1/2
0.5000
7/8
0.875
0.850
1.010
0.969
31/64
0.504
0.464
9/16
0.5625
15/16
0.938
0.909
1.083
1.037
35/64
0.568
0.526
5/8
0.6250
1-1/16
1.062
1.031
1.227
1.175
39/64
0.631
0.587
3/4
0.7500
1-1/4
1.250
1.212
1.443
1.382
47/64
0.758
0.710
7/8
0.8750
1-7/16
1.438
1.394
1.660
1.589
55/64
0.885
0.833
1
1.0000
1-5/8
1.625
1.575
1.876
1.796
63/64
1.012
0.956
1-1/8
1.1250
1-13/16
1.812
1.756
2.093
2.002
1-7/64
1.139
1.079
1-1/4
1.2500
2
2.000
1.938
2.309
2.209
1-7/32
1.251
1.187
1-3/8
1.3750
2-3/16
2.188
2.119
2.526
2.416
1-11/32
1.378
1.310
1-1/2
1.5000
2-3/8
2.375
2.300
2.742
2.622
1-15/32
1.505
1.433
1-5/8
1.6250
2-9/16
2.562
2.481
2.959
2.828
1-19/32
1.632
1.556
1-3/4
1.7500
2-3/4
2.750
2.662
3.175
3.035
1-23/32
1.759
1.679
2
2.0000
3-1/8
3.125
3.025
3.608
3.449
1-31/32
2.013
1.925
2-1/4
2.2500
3-1/2
3.500
3.388
4.041
3.862
2-13/64
2.251
2.155
2-1/2
2.5000
3-7/8
3.875
3.750
4.474
4.275
2-29/64
2.505
2.401
2-3/4
2.7500
4-1/4
4.250
4.112
4.907
4.688
2-45/64
2.759
2.647
3
3.0000
4-5/8
4.625
4.475
5.340
5.102
2-61/64
3.013
2.893
3-1/4
3.2500
5
5.000
4.838
5.774
5.515
3-3/16
3.252
3.124
3-1/2
3.5000
5-3/8
5.375
5.200
6.207
5.928
3-7/16
3.506
3.370
3-3/4
3.7500
5-3/4
5.750
5.562
6.640
6.341
3-11/16
3.760
3.616
4
4.0000
6-1/8
6.125
5.925
7.073
6.755
3-15/16
4.014
3.862
NUTS
Heavy hex
Steel & Stainless
x
x
Grade-5
*
*
*
Grade-A
Grade-C
STEEL
x
*
DH
A 194 Grade-2H
A 563 Grade-DH
*
x
DH3
A 563 Grade-DH3
Description
A six-sided internally threaded fastener which is both thicker and wider across the flats than a same-sized finished hex nut. Nuts in sizes 7/16 & smaller
shall be double chamfered. Larger sizes are either double chamfered or chamfered on top with a washer faced bearing surface.
Applications/
Advantages
This is the strongest of all comparably-graded nuts because of its greater length of thread engagement and greater resistance to dilation (widening or
stretching). Grade-5 nuts are used with medium-carbon cap screws/bolts Grade-A nuts are used with low-carbon heavy hex bolts. Grade-C nuts are
recommended for use with A-325 structural bolts. Grade-2H nuts are recommended for use with bolts in high-pressure and high-temperature service.
Grade-DH nuts are recommended for use with A-490, Type-1 structural bolts and Grade-DH3 nuts for use with A-490, Type-3 structural bolts.
Material
Nuts shall be made from a steel which conforms to the following chemical composition requirements (heat analysis)-Grade-5-- Carbon: 0.55% maximum; Manganese: 0.30% max; Phosphorus: 0.05% maximum; Sulfur: 0.15% maximum.
Grades-A & C-- Carbon: 0.55% maximum; Phosphorus: 0.12% maximum; Sulfur: 0.023% maximum.
A 194 Grade-2H-- Carbon: 0.40% min; Manganese: 1.00% max; Phosphorus: 0.04% max; Sulfur: 0.05% max; Silicon: 0.40% max.
A 563 Grade-DH-- Carbon: 0.20-0.55%; Manganese: 0.60% minimum; Phosphorus: 0.04% maximum; Sulfur: 0.05% maximum.
Grade-DH3-- Carbon: 0.20-0.53%; Manganese: 0.40% minimum; Phosphorus: 0.046% maximum; Sulfur: 0.050% maximum;
Copper: 0.20% minimum; Chromium: 0.45% minimum; (Either Nickel: 0.20% minimum or Molybdenum: 0.15% minimum, may be used).
Heat
Treatment
Grade-2H: Nuts are heat treated by quenching in a liquid medium from a temp above the transformation temp and tempering at a temp of at least 850°F.
Grades-C, DH & DH3: Nuts are heat treated by quenching in a liquid medium from a temp above the transformation temp and tempering at a temp of at
least 800°F.
Core
Hardness
Grade-5: Rockwell C32 max.
Grade-A: Rockwell B68 - C32
Grade-C: Rockwell B78 - C38
A 194 Grade-2H; A 563 Grades DH & DH3: Rockwell C24 - C38
Proof Load
Grade-5: 1/4 thru 1” Diam, Coarse- 133,000 psi.; Fine- 120,000 psi.
Grade-A: Coarse- 100,000 psi.; Fine- 90,000 psi.
Grade-C: 144,000 psi.
Grade-2H: 150,000 psi.
Grades-DH & DH3: 175,000 psi.
Plating
See Appendix-A for plating information.
18-8 STAINLESS STEEL
Description
A six-sided internally threaded fastener which is both thicker and wider across the flats than a same-sized finished hex nut, made of 18-8 stainless. Nuts
in sizes 7/16 & smaller shall be double chamfered. Larger sizes are either double chamfered or chamfered on top with a washer faced bearing surface.
Applications/
Advantages
This is the strongest of all 18-8 stainless hex nuts because of its greater length of thread engagement and greater resistance to widening or stretching.
Material
Nuts shall be made from one of the following austenitic stainless alloys: 303, 303Se, 304, XM7, all of which are characterized as having a chromium
content of 18% and a nickel content of 8%.
Heat
Treatment
The austenitic alloys develop their strength through work hardening during the fastener manufacturing process, as seen from the hardness properties
below. The only heat treatment normally available on austenitic stainless alloys is annealing, which is done at approximately 1900°F to a dead soft
condition and is not normally thermally reversible.
Hardness
1/4 through 5/8”: Rockwell B95 - C32
3/4 through 1”: Rockwell B80 - C32
Proof Load
1/4 through 5/8”: 100,000 psi
3/4 through 1”: 85,000 psi.
*Product standards require all grade-marked nuts 1/4” diameter and larger to have a raised or depressed insignia identifying its manufacturer.
“X” represnets one location such a marking may appear.
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